As the title says, I want to know when the treewidth of a bipartite graph is bounded by a constant. What families of graphs are both bipartite and bounded treewidth?
More generally, I would like to find a property $P$ such that for any bipartite graph $G$ the following statement is true: "the treewidth of $G$ is bound by a constant if and only if $G$ satisfies property $P$."